We propose to investigate the microviscosity of a variety of anionic, cationic and neutral micelles using novel fluorescent probes capable of forming excimers intramolecularly. The dependence of the ratio of normal fluorescence to excimer fluorescence on viscosity will be determined for several of these probes. Using this dependence as a reference, the microviscosities of micelles will be determined by examining the excimer yields of these probes while solubilized in micelles. Probes that bind to the micellar core as well as probes that bind to the micellar surface will be examined. The dependence of the observed microviscosities on temperature, aging time, electrolyte concentration, and length of surfactant will also be determined.